Cathode assembly for electric discharge tubes



Nov. 29, 1949 H. J. DE WEYER 2,439,367

CATHODE ASSEMBLY FOR ELECTRIC DISCHARGE TUBES Filed Dec. 6, 1947 H.J. DE WEYER INVENTOR AGENT Patented Nov. 29, 1949 Henricus Johannes de Weyer, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application December 6, 1947, Serial No. 790,105. In the Netherlands November 13, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires November 13, 1966 4 Claims.

1 This invention relates to an electric discharge tube comprising an indirectly heated cathode which is formed by swaging and, drawing or rolling a tubular conductor containing one or more It has now been found that special advantages are obtained if the cathode is flattened at definite points. Thus, for example, the thermal losses are materially reduced if in an electric discharge tube comprising an indirectly heated cathode formed by swaging and drawing 'or rolling a tubular conductor containing one or more conductors with the interposition of powdered insulating material, which cathode is one or several times bent and, at least over part of its length, flattened, inactive cathode parts are flattened, according to the invention, at the points of support in such manner that the cathode engages the supporting members only with a narrow edge. This yields the advantage that not only less heat is dissipated but consequently also the temperature distribution becomes more even throughout the length of the cathode. Moreover, the cathode becomes rigid, i. e. that it does not tend to alter its shape spontaneously. In addition, such a cathode is adapted to be supported in a very simple manner in insulating centring members.

If such a cathode is one or more times bent into the shape of a hair-pin or in zigzag fashion, it may be flattened at the bends and at the ends. This flattening of the bends is preferably effected in a direction at right angles to the plane of the bend, so that the bend becomes rigid, whilst the heat transference to a supporting member engaging the bend, for example a tension spring, may be low, since the flattened bend of the cathode rests with a narrow edge on such a supporting member. Since the bend is rigid such a supporting member may, moreover, be very narrow. The flattened curved parts may he slipped through a narrow slit in a centring member and hooked to a supporting member.

The flattened parts near the ends of the cathode serve to fasten the cathode ends in a centring member,- these flattened parts being, for ex-' ample, introduced into an aperture having a narrow slit in such manner as to extend at right angles to the longitudinal direction of the slit and prevent the cathode ends from being drawn through the slit. In this case it is consequently not necessary to secure cross-bars or supporting wires to the cathode ends, so that the dissipation of heat will be small. Moreover, the flattened parts at the ends of the cathode rest with a narrow edge onthe centring member, for example, a mica disc, so that only little heat is dissipated. In accordance with the shape of the aperture in the centring member the ends may be flattened in the sameplane as the bends or at right angles thereto.

It has been found that a cathode according to the invention exhibits a very uniform temperature distribution throughout its active length,

In order that the invention may be more clear- 1y understood and readily carried into effect, it will now be described more fully with reference to the accompanying-drawing, in which:

Figure 1 is a front view of a cathode assembly according to the invention,

Fig. 2 is a side view of the cathode assembly,

Fig. 3 is a sectional view taken along line 3--3 of Fig. 1, and

Fig. 4 is a transverse sectional view on an enlarged scale of the cathode shown in Fig. 1.

In the drawing the reference numeral I designates the cathode which in the present case is bent into the shape of a hair-pin and supported by means of the centring members 2 and 3. As shown in Fig. 4 cathode l comprises a central filament 6 surrounded by tubular outer conductor In, the intervening space being filled with a powdered insulating material Il. At about 0.5 mm. from its ends the cathode l is provided with flattened parts 4 which extend at right angles to the plane of the hair-pin and prevent the ends from being drawn through the apertures l, 8 of the centring member 2 consisting, for example, of mica. To this end these apertures exhibit preferably a wide part I for the introduction of the flattened cathode end 4 and a narrow part 8 into which the round part of the cathode can just be slipped but through which the flattened part 4 cannot pass. The narrow part 8 may either exhibit the form of a slit to which the plane of the flattened part 4 extends at right angles, or be formed in a known manner by superposition of two insulating members in such manner that the cathode end is locked in a small aperture. The curved part is likewise flattened, at least partly; but inethis case in-the plane of the bend, slipped through a slit 8 of the member 3 and hooked to the tension spring 9. The cathode is heated by means of the filament 6 and is adapted to be flattened in a yerysimple manner by impact or pressure with the aid of a stamp. For this purpose the cathode is bent on a jig and flattened at the desired rp'oints; the cathode becomes rigid, i. e. -.thatwitno longer tends to alter its shape after. removal of the jig. This is promoted by the fact that the curved parts are flattened in the plane of, the hair-pin as shown in the drawing. The supply to the cathode body is preferably effected at a point of suspension in a bend. It is obvious that the cathode may consist 'of a plurality of parts which are bent to and fro one or several times, for example hair-pin shaped parts'which-may, extendin one plane or in' a cylindrical plane; rInstead of being I hair-pin shaped, the cathodemay also be V- or U-shaped, staggered orbent in any convenient Way.

"What I claim: i511?- l 1: A cathode assembly for' an electric discharge tube,-compr,ising a supporting member and an indirectlyheatedmcathode member having an inner conductor, and'outericonductor spacedly surrounding said inner conductor and powdered insulating material separating and compactly filling the space betweenr-lthe" inner and outer conductors, said outer conductor comprising a first tubular'portion-candra second flattened portion having a narrowvedge, said second portion engaging said supporting member with the said narrow edge thereof. 1

,1 2. A cathoderassembly. for an electric discharge tube; comprising :asupporting member and an indirectly heated pat-bode member having a bent portion and aastraight-portion and comprising an inner conductor; an outerrconductor spacedly surrounding said inner conductor "and powdered insulating material separating and compactly filling the space-betweenzithe"inner'and outer conductors, the outer conductor at said bent'portion being flattenedr-in theplanez'of the bend and having a narrow edge and at said straight por- 4 tion being tubular, said bent portion engaging said supporting member at said narrow edge.

3. A cathode assembly for an electric discharge tube, comprising a supporting member and an indirectly heated cathode member having an in- 7 nor conductor, 'anouter conductor spacedly surrounding said inner conductor and powdered insulating material separating and compactly filling'the space between the inner and outer conducto1's,.'said "outer conductor comprising a first tubular portion and second flattened end portions each having a narrow edge, said second end portions engaging said supporting member with the said narrow edge thereof.

4. A'cathode assembly for an electric discharge "tube, comprising an upper insulating plate mem- 1' compactly filling the space between the inner and outer conductors, and a cathode tensioning member positioned above said upper insulating member,-said outer conductor comprising tubular portions intermediate the bent and end portionsof the said cathode and flattened portions at said bent and end portions each provided with a narrowedge, said end portions engaging said loweri'nsulating member with the narrow edge thereof and said bent portion being positioned within said slit and engaging said tensioning member with the narrow edge thereof.

HENRICUS JOHANNES DE VJEYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,700,454 Schumacher Jan. 29, 1929 2,014,787 Smithells et al. Sept. 17, 1935 2,112,969 Mavrogenis Apr. 5, 1938 

